Inkjet printing apparatuses have widely been used in printing apparatuses, copying machines, and the like because low noise, low apparatus cost, low running cost, compact apparatus, and the like can be facilitated.
A conventional serial inkjet printing apparatus prints one page by repeating main scanning of scanning a printhead in the main scanning direction and sub-scanning of conveying a printing medium in the sub-scanning direction. The serial inkjet printing apparatus ensures a memory (print buffer) having enough capacity to store print data of at least one scanning. After all print data of one scanning is stored in the print buffer, main scanning of the printhead starts. Especially with the development of color printing apparatuses and an increase in resolution in response to demands for higher image qualities, the capacity necessary for the print buffer increases. The printing apparatus requires an expensive larger-capacity memory, resulting in a high apparatus cost.
To solve the conventional problem, Japanese Patent Laid-Open No. 58-146929 discloses a technique of constituting a memory whose capacity is smaller than a capacity for storing print data of one scanning, managing print data by a storage address, and efficiently exploiting the small-capacity memory.
Japanese Patent Laid-Open No. 11-227181 discloses a technique of reducing a memory capacity for storing print data by transmitting print data corresponding to a nozzle for use from a host apparatus to a printing apparatus by using a printhead having a plurality of nozzles in the sub-scanning direction and using a printing apparatus which repeats main scanning and sub-scanning to form an image.
Japanese Patent Laid-Open No. 11-259248 discloses a technique of achieving reduction in memory capacity and high-speed printing by starting main scanning of a printhead before the completion of storing print data of one main scanning in a memory. This proposal assumes that enough data to complete scanning is always received during scanning/printing while main scanning of the printhead is executed. Thus, the memory capacity cannot be greatly reduced.
However, no proposal realizes high-speed printing at lower cost by considering print data and the main scanning start timing without changing an existing arrangement.